Vardhamana, son of a Hindu ruler in what is now Bihar, north of the Ganges, sets off from home at the age of about thirty, leaving his young wife and a daughter. He has chosen the life of a beggar, following the ascetic ideals of his master, Parsva, who lived about 250 years previously. Twelve years later he has achieved the high status described as tirthankara. He is the 24th man to become a tirthankara. Parsva was the 23rd.

Such is the traditional account of the beginning of the Indian religion known as Jainism - from the Sanskrit word jina, meaning 'conqueror' (in this case of the flesh). Vardhamana's achievement wins him the title by which he is also known - Mahavira, or 'great hero'.

Mahavira's rejection of the privileged life into which he was born is a familiar start for religious leaders (closely mirrored, for example, in the stories of Gautama Buddha or Francis of Assisi). But in India, in the 6th century BC, there is a topical reason for his action. Mahavira is of the Kshatriya or warrior caste, at a time when the Brahmans (the priestly caste) have established a rigidly hierarchical society. Power is kept strictly in the priests' hands, through their control of the animal sacrifices in the temples.

The guiding principles of Jainism reflect a very specific rejection of the temple sacrifices and the Hindu caste system.

At the heart of the Jain doctrine is the principle of ahimsa. This means 'non-violence', but it is interpreted as something more extreme - the avoidance of taking any form of life. The reason is that all living things are believed to share with mankind the possession of a soul, the jiva.

Each human life, as in Hinduism, is judged in terms of its accumulated karma. But for the Jains the karma is more physical. It is like an impurity which clogs and weighs down the soul. An average human being is certain to accumulate this harmful karma (much like middle-aged spread), but a true ascetic can reduce it to nothing until the soul is unimpeded. As in Hinduism, he can then achieve moksha (see karma and moksha).

Sky clad and white clad: from the 1st century BC

By the end of his life Mahavira has enough disciples to spread his teaching. Jainism eventually becomes well established in western India and in the south. But in the 1st century BC the two regions have a doctrinal split which survives to this day.

The southern Jain argue that the ideal of owning nothing means that one must go naked. The western Jain, less absolute in their doctrine, adopt a simple white robe. The sectarian names reflect the difference: digambara ('sky-clad') in the south, svetambara ('white-clad') in the west. In modern society the southern Jains no longer appear in public naked.

The need to avoid killing even the tiniest creature has made Jainism more suitable for city dwellers than for farmers. It has been a religion mainly of merchants and traders. As a precaution against the accidental swallowing of an insect, Jain devotees can be seen in India wearing light muslin masks over their mouths when they walk out of doors.

Each individual is responsible for his or her own karma, so there is no need in the Jain scheme of things for a god. Nevertheless the twenty-four tirthankaras have almost divine status. In the exquisitely simple and uncluttered Jain temples, images of these holy men (often with gleaming jewelled eyes) are tended with devotion.